[PATCH 3.18 091/151] NFSv4: Ensure we reference the inode for return-on-close in delegreturn

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.mykleb...@primarydata.com>

commit ea7c38fef0b774a5dc16fb0ca5935f0ae8568176 upstream.

If we have to do a return-on-close in the delegreturn code, then
we must ensure that the inode and super block remain referenced.

Cc: Peng Tao <tao.p...@primarydata.com>
Signed-off-by: Trond Myklebust <trond.mykleb...@primarydata.com>
Reviewed-by: Peng Tao <tao.p...@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 fs/nfs/internal.h |   22 +++++++++++++++++++++-
 fs/nfs/nfs4proc.c |   14 +++++++++-----
 fs/nfs/super.c    |    9 ++++++---
 3 files changed, 36 insertions(+), 9 deletions(-)

--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -377,7 +377,7 @@ extern struct rpc_stat nfs_rpcstat;
 
 extern int __init register_nfs_fs(void);
 extern void __exit unregister_nfs_fs(void);
-extern void nfs_sb_active(struct super_block *sb);
+extern bool nfs_sb_active(struct super_block *sb);
 extern void nfs_sb_deactive(struct super_block *sb);
 
 /* namespace.c */
@@ -495,6 +495,26 @@ extern int nfs41_walk_client_list(struct
                                struct nfs_client **result,
                                struct rpc_cred *cred);
 
+static inline struct inode *nfs_igrab_and_active(struct inode *inode)
+{
+       inode = igrab(inode);
+       if (inode != NULL && !nfs_sb_active(inode->i_sb)) {
+               iput(inode);
+               inode = NULL;
+       }
+       return inode;
+}
+
+static inline void nfs_iput_and_deactive(struct inode *inode)
+{
+       if (inode != NULL) {
+               struct super_block *sb = inode->i_sb;
+
+               iput(inode);
+               nfs_sb_deactive(sb);
+       }
+}
+
 /*
  * Determine the device name as a string
  */
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5130,9 +5130,13 @@ static void nfs4_delegreturn_done(struct
 static void nfs4_delegreturn_release(void *calldata)
 {
        struct nfs4_delegreturndata *data = calldata;
+       struct inode *inode = data->inode;
 
-       if (data->roc)
-               pnfs_roc_release(data->inode);
+       if (inode) {
+               if (data->roc)
+                       pnfs_roc_release(inode);
+               nfs_iput_and_deactive(inode);
+       }
        kfree(calldata);
 }
 
@@ -5189,9 +5193,9 @@ static int _nfs4_proc_delegreturn(struct
        nfs_fattr_init(data->res.fattr);
        data->timestamp = jiffies;
        data->rpc_status = 0;
-       data->inode = inode;
-       data->roc = list_empty(&NFS_I(inode)->open_files) ?
-                   pnfs_roc(inode) : false;
+       data->inode = nfs_igrab_and_active(inode);
+       if (data->inode)
+               data->roc = nfs4_roc(inode);
 
        task_setup_data.callback_data = data;
        msg.rpc_argp = &data->args;
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -405,12 +405,15 @@ void __exit unregister_nfs_fs(void)
        unregister_filesystem(&nfs_fs_type);
 }
 
-void nfs_sb_active(struct super_block *sb)
+bool nfs_sb_active(struct super_block *sb)
 {
        struct nfs_server *server = NFS_SB(sb);
 
-       if (atomic_inc_return(&server->active) == 1)
-               atomic_inc(&sb->s_active);
+       if (!atomic_inc_not_zero(&sb->s_active))
+               return false;
+       if (atomic_inc_return(&server->active) != 1)
+               atomic_dec(&sb->s_active);
+       return true;
 }
 EXPORT_SYMBOL_GPL(nfs_sb_active);
 


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